Haplostatus dakarensis sp. nov.

(Fig. 439)

Typematerial. Holotype (intact ♀. MNHN-IU-2014- 21462), paratype (intact ♀, MNUN-IU-2014-21463), and dissectedparatype (♀, figured) from Cystodytes roseolus Hartmeyer, 1912 (MNHN-IT-2008-2603 = MNHNA3/ CYS/36), off Dakar, Senegal, Leung Tar kit coll .

Additionalmaterial. 3 ♀♀ (MNHN-IU-2018-1915) from the same host species and same locality as the type material.

Etymology. The name of the new species refers to the type locality, Dakar, Senegal ..

Descriptionoffemale. Body (Fig. 439A) vermiform, cylindrical, slightly arched ventrally, narrowing anteriorly and posteriorly, without any metameric subdivision. Body length 4.42 mm in holotype; greatest width 1.12 mm in middle; body lengths of 2 paratypes 3.04 and 5.20 mm. Body surface smooth, without ornamentation of setules or wrinkles. Freeurosome (Fig. 439B, C) short, occupying 7% of total body length, obscurely 3-segmented, with additional partial suture line (or wrinkle) dorsally, anterior to first urosomite and 4 faint sclerotization bands on dorsal side (Fig. 439C). Last urosomite (anal somite) weakly bilobed; each lobe tipped with small, pointed, claw-like process (Fig. 439B, C).

Rostrum (Fig. 439D, E) distinct, slightly widerthan long, tapering towards rounded distal margin. Antennule (Fig. 439F, G) lobate, unsegmented, widerthan long, ornamented with few, minute spinules subdistally. Antenna (Fig. 439H) located deep inside pre-oral cavity (Fig. 439D); stout, 2-segmented, both segments unarmed; distal (endopodal) segment strongly tapering, fused to terminal claw, leaving only partial non-sclerotized region as vestige of articulation.

Labrum (Fig. 439I) broadening posteriorly, located deep inside pre-oral cavity, unornamented, with slightly concave posterior margin. Mandibles, maxillules, maxillae, maxillipeds and legs absent.

Male. Unknown.

Remarks. Haplostatus incubatrix, the type species of the genus, is associated with the compound ascidian Cystodytes dellechiajei (Della Valle, 1877) found in the Mediterranean Sea (Illg & Dudley, 1961). Haplostatus dakarensis sp. nov. differs from thetype species as follows: (1) the body surface is smooth, without setules or wrinkles, compared to the presence of an ornamentation of fine setules over the entire body surface in H. incubatrix, as described by Illg & Dudley (1961); (2) the antennule is wider than long and carries a few spinules, compared to the antennule of H. incubatrix which is longer than wide (Illg & Dudley, 1961); (3) the endopod and terminal claw of the antenna are fused, compared to the free terminal claw of H. incubatrix; and (4) the mouthparts are all lacking, whereas one pair of mouthparts is retained in H. incubatrix .